qemu/hw/acpi/vmgenid.c
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   1/*
   2 *  Virtual Machine Generation ID Device
   3 *
   4 *  Copyright (C) 2017 Skyport Systems.
   5 *
   6 *  Author: Ben Warren <ben@skyportsystems.com>
   7 *
   8 * This work is licensed under the terms of the GNU GPL, version 2 or later.
   9 * See the COPYING file in the top-level directory.
  10 *
  11 */
  12
  13#include "qemu/osdep.h"
  14#include "qmp-commands.h"
  15#include "hw/acpi/acpi.h"
  16#include "hw/acpi/aml-build.h"
  17#include "hw/acpi/vmgenid.h"
  18#include "hw/nvram/fw_cfg.h"
  19#include "sysemu/sysemu.h"
  20
  21void vmgenid_build_acpi(VmGenIdState *vms, GArray *table_data, GArray *guid,
  22                        BIOSLinker *linker)
  23{
  24    Aml *ssdt, *dev, *scope, *method, *addr, *if_ctx;
  25    uint32_t vgia_offset;
  26    QemuUUID guid_le;
  27
  28    /* Fill in the GUID values.  These need to be converted to little-endian
  29     * first, since that's what the guest expects
  30     */
  31    g_array_set_size(guid, VMGENID_FW_CFG_SIZE - ARRAY_SIZE(guid_le.data));
  32    guid_le = vms->guid;
  33    qemu_uuid_bswap(&guid_le);
  34    /* The GUID is written at a fixed offset into the fw_cfg file
  35     * in order to implement the "OVMF SDT Header probe suppressor"
  36     * see docs/specs/vmgenid.txt for more details
  37     */
  38    g_array_insert_vals(guid, VMGENID_GUID_OFFSET, guid_le.data,
  39                        ARRAY_SIZE(guid_le.data));
  40
  41    /* Put this in a separate SSDT table */
  42    ssdt = init_aml_allocator();
  43
  44    /* Reserve space for header */
  45    acpi_data_push(ssdt->buf, sizeof(AcpiTableHeader));
  46
  47    /* Storage for the GUID address */
  48    vgia_offset = table_data->len +
  49        build_append_named_dword(ssdt->buf, "VGIA");
  50    scope = aml_scope("\\_SB");
  51    dev = aml_device("VGEN");
  52    aml_append(dev, aml_name_decl("_HID", aml_string("QEMUVGID")));
  53    aml_append(dev, aml_name_decl("_CID", aml_string("VM_Gen_Counter")));
  54    aml_append(dev, aml_name_decl("_DDN", aml_string("VM_Gen_Counter")));
  55
  56    /* Simple status method to check that address is linked and non-zero */
  57    method = aml_method("_STA", 0, AML_NOTSERIALIZED);
  58    addr = aml_local(0);
  59    aml_append(method, aml_store(aml_int(0xf), addr));
  60    if_ctx = aml_if(aml_equal(aml_name("VGIA"), aml_int(0)));
  61    aml_append(if_ctx, aml_store(aml_int(0), addr));
  62    aml_append(method, if_ctx);
  63    aml_append(method, aml_return(addr));
  64    aml_append(dev, method);
  65
  66    /* the ADDR method returns two 32-bit words representing the lower and
  67     * upper halves * of the physical address of the fw_cfg blob
  68     * (holding the GUID)
  69     */
  70    method = aml_method("ADDR", 0, AML_NOTSERIALIZED);
  71
  72    addr = aml_local(0);
  73    aml_append(method, aml_store(aml_package(2), addr));
  74
  75    aml_append(method, aml_store(aml_add(aml_name("VGIA"),
  76                                         aml_int(VMGENID_GUID_OFFSET), NULL),
  77                                 aml_index(addr, aml_int(0))));
  78    aml_append(method, aml_store(aml_int(0), aml_index(addr, aml_int(1))));
  79    aml_append(method, aml_return(addr));
  80
  81    aml_append(dev, method);
  82    aml_append(scope, dev);
  83    aml_append(ssdt, scope);
  84
  85    /* attach an ACPI notify */
  86    method = aml_method("\\_GPE._E05", 0, AML_NOTSERIALIZED);
  87    aml_append(method, aml_notify(aml_name("\\_SB.VGEN"), aml_int(0x80)));
  88    aml_append(ssdt, method);
  89
  90    g_array_append_vals(table_data, ssdt->buf->data, ssdt->buf->len);
  91
  92    /* Allocate guest memory for the Data fw_cfg blob */
  93    bios_linker_loader_alloc(linker, VMGENID_GUID_FW_CFG_FILE, guid, 4096,
  94                             false /* page boundary, high memory */);
  95
  96    /* Patch address of GUID fw_cfg blob into the ADDR fw_cfg blob
  97     * so QEMU can write the GUID there.  The address is expected to be
  98     * < 4GB, but write 64 bits anyway.
  99     * The address that is patched in is offset in order to implement
 100     * the "OVMF SDT Header probe suppressor"
 101     * see docs/specs/vmgenid.txt for more details.
 102     */
 103    bios_linker_loader_write_pointer(linker,
 104        VMGENID_ADDR_FW_CFG_FILE, 0, sizeof(uint64_t),
 105        VMGENID_GUID_FW_CFG_FILE, VMGENID_GUID_OFFSET);
 106
 107    /* Patch address of GUID fw_cfg blob into the AML so OSPM can retrieve
 108     * and read it.  Note that while we provide storage for 64 bits, only
 109     * the least-signficant 32 get patched into AML.
 110     */
 111    bios_linker_loader_add_pointer(linker,
 112        ACPI_BUILD_TABLE_FILE, vgia_offset, sizeof(uint32_t),
 113        VMGENID_GUID_FW_CFG_FILE, 0);
 114
 115    build_header(linker, table_data,
 116        (void *)(table_data->data + table_data->len - ssdt->buf->len),
 117        "SSDT", ssdt->buf->len, 1, NULL, "VMGENID");
 118    free_aml_allocator();
 119}
 120
 121void vmgenid_add_fw_cfg(VmGenIdState *vms, FWCfgState *s, GArray *guid)
 122{
 123    /* Create a read-only fw_cfg file for GUID */
 124    fw_cfg_add_file(s, VMGENID_GUID_FW_CFG_FILE, guid->data,
 125                    VMGENID_FW_CFG_SIZE);
 126    /* Create a read-write fw_cfg file for Address */
 127    fw_cfg_add_file_callback(s, VMGENID_ADDR_FW_CFG_FILE, NULL, NULL, NULL,
 128                             vms->vmgenid_addr_le,
 129                             ARRAY_SIZE(vms->vmgenid_addr_le), false);
 130}
 131
 132static void vmgenid_update_guest(VmGenIdState *vms)
 133{
 134    Object *obj = object_resolve_path_type("", TYPE_ACPI_DEVICE_IF, NULL);
 135    uint32_t vmgenid_addr;
 136    QemuUUID guid_le;
 137
 138    if (obj) {
 139        /* Write the GUID to guest memory */
 140        memcpy(&vmgenid_addr, vms->vmgenid_addr_le, sizeof(vmgenid_addr));
 141        vmgenid_addr = le32_to_cpu(vmgenid_addr);
 142        /* A zero value in vmgenid_addr means that BIOS has not yet written
 143         * the address
 144         */
 145        if (vmgenid_addr) {
 146            /* QemuUUID has the first three words as big-endian, and expect
 147             * that any GUIDs passed in will always be BE.  The guest,
 148             * however, will expect the fields to be little-endian.
 149             * Perform a byte swap immediately before writing.
 150             */
 151            guid_le = vms->guid;
 152            qemu_uuid_bswap(&guid_le);
 153            /* The GUID is written at a fixed offset into the fw_cfg file
 154             * in order to implement the "OVMF SDT Header probe suppressor"
 155             * see docs/specs/vmgenid.txt for more details.
 156             */
 157            cpu_physical_memory_write(vmgenid_addr, guid_le.data,
 158                                      sizeof(guid_le.data));
 159            /* Send _GPE.E05 event */
 160            acpi_send_event(DEVICE(obj), ACPI_VMGENID_CHANGE_STATUS);
 161        }
 162    }
 163}
 164
 165static void vmgenid_set_guid(Object *obj, const char *value, Error **errp)
 166{
 167    VmGenIdState *vms = VMGENID(obj);
 168
 169    if (!strcmp(value, "auto")) {
 170        qemu_uuid_generate(&vms->guid);
 171    } else if (qemu_uuid_parse(value, &vms->guid) < 0) {
 172        error_setg(errp, "'%s. %s': Failed to parse GUID string: %s",
 173                   object_get_typename(OBJECT(vms)), VMGENID_GUID, value);
 174        return;
 175    }
 176
 177    vmgenid_update_guest(vms);
 178}
 179
 180/* After restoring an image, we need to update the guest memory and notify
 181 * it of a potential change to VM Generation ID
 182 */
 183static int vmgenid_post_load(void *opaque, int version_id)
 184{
 185    VmGenIdState *vms = opaque;
 186    vmgenid_update_guest(vms);
 187    return 0;
 188}
 189
 190static const VMStateDescription vmstate_vmgenid = {
 191    .name = "vmgenid",
 192    .version_id = 1,
 193    .minimum_version_id = 1,
 194    .post_load = vmgenid_post_load,
 195    .fields = (VMStateField[]) {
 196        VMSTATE_UINT8_ARRAY(vmgenid_addr_le, VmGenIdState, sizeof(uint64_t)),
 197        VMSTATE_END_OF_LIST()
 198    },
 199};
 200
 201static void vmgenid_handle_reset(void *opaque)
 202{
 203    VmGenIdState *vms = VMGENID(opaque);
 204    /* Clear the guest-allocated GUID address when the VM resets */
 205    memset(vms->vmgenid_addr_le, 0, ARRAY_SIZE(vms->vmgenid_addr_le));
 206}
 207
 208static void vmgenid_realize(DeviceState *dev, Error **errp)
 209{
 210    VmGenIdState *vms = VMGENID(dev);
 211
 212    if (!bios_linker_loader_can_write_pointer()) {
 213        error_setg(errp, "%s requires DMA write support in fw_cfg, "
 214                   "which this machine type does not provide", VMGENID_DEVICE);
 215        return;
 216    }
 217
 218    /* Given that this function is executing, there is at least one VMGENID
 219     * device. Check if there are several.
 220     */
 221    if (!find_vmgenid_dev()) {
 222        error_setg(errp, "at most one %s device is permitted", VMGENID_DEVICE);
 223        return;
 224    }
 225
 226    qemu_register_reset(vmgenid_handle_reset, vms);
 227}
 228
 229static void vmgenid_device_class_init(ObjectClass *klass, void *data)
 230{
 231    DeviceClass *dc = DEVICE_CLASS(klass);
 232
 233    dc->vmsd = &vmstate_vmgenid;
 234    dc->realize = vmgenid_realize;
 235    dc->hotpluggable = false;
 236    set_bit(DEVICE_CATEGORY_MISC, dc->categories);
 237
 238    object_class_property_add_str(klass, VMGENID_GUID, NULL,
 239                                  vmgenid_set_guid, NULL);
 240    object_class_property_set_description(klass, VMGENID_GUID,
 241                                    "Set Global Unique Identifier "
 242                                    "(big-endian) or auto for random value",
 243                                    NULL);
 244}
 245
 246static const TypeInfo vmgenid_device_info = {
 247    .name          = VMGENID_DEVICE,
 248    .parent        = TYPE_DEVICE,
 249    .instance_size = sizeof(VmGenIdState),
 250    .class_init    = vmgenid_device_class_init,
 251};
 252
 253static void vmgenid_register_types(void)
 254{
 255    type_register_static(&vmgenid_device_info);
 256}
 257
 258type_init(vmgenid_register_types)
 259
 260GuidInfo *qmp_query_vm_generation_id(Error **errp)
 261{
 262    GuidInfo *info;
 263    VmGenIdState *vms;
 264    Object *obj = find_vmgenid_dev();
 265
 266    if (!obj) {
 267        error_setg(errp, "VM Generation ID device not found");
 268        return NULL;
 269    }
 270    vms = VMGENID(obj);
 271
 272    info = g_malloc0(sizeof(*info));
 273    info->guid = qemu_uuid_unparse_strdup(&vms->guid);
 274    return info;
 275}
 276